1. Field of the Invention
The invention refers to a low temperature device for the cooling of small samples. It can be used in the application of different spectroscopic methods, especially at X-ray and neutron diffraction, and for the investigation of different phases as well as electrical properties.
At such spectroscopic methods the temperature motion of atoms shall be reduced by cooling, temperature dependent phases shall be investigated, respectively. For this constant temperatures are necessary for longer periods.
2. Description of the Prior Art
It is known that measurements on small samples are performed at low temperatures by passing a temperature controlled gas stream over a sample. The producing of the cold gas stream is either done by evaporation of e.g. liquid nitrogen with following temperature control (System FR 524, Enraf Nonius, Delft, Enraf Nonius bulletin (1964) or by cooling gaseous nitrogen in a heat exchanger (System Lt-1, Nicolet/Fremont, California (1979)). At both systems a distance of approximately 80-150 cm is to be bridged by insulated tubes from the coldest point of the gaseous stream to the sample.
In order to achieve the lowest possible temperature at the sample there must be a high stream speed because of the long distances at which the gas, according to experience, warms up. This causes a high consumption of liquid gas. Even at high stream speeds temperatures only above 100 K. can be achieved with liquid nitrogen in the surrounding of the sample. In addition long distances reduce temperature stability at the sample's position if the surrounding temperature differs.